Stepless golf shaft with multiple taper rates in mid section

ABSTRACT

A stepless golf shaft includes; a butt portion having: a proximal end configured to be attached to a golf grip; and a distal end; a tip portion having; a distal end configured to be attached to a golf club head; and a proximal end; and a midsection connecting the proximal end of the tip portion with the distal end of the butt portion, the midsection including; a first portion having a first outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a first taper rate and not having any step changes in the first outer diameter; and a second portion having a second outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a second taper rate, where the second taper rate is different than the first taper rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 63/092,051, filed on Oct. 15, 2020. The entire disclosure of the application referenced above is incorporated herein by reference.

FIELD

The present disclosure relates to golf shafts and more particularly to stepless golf shafts with multiple different taper rates.

BACKGROUND

The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Some (e.g., steel) golf shafts included one or more steps in a midsection between a butt portion and a tip portion. Such golf shafts may be referred to as stepped golf shafts. A golf club head is connected to the tip portion of a golf club shaft. A grip is attached to the butt portion of the golf club. The midsection of a golf club may also be referred to as a transitional section and is disposed between the tip portion and the butt portion.

Other types of golf shafts do not include any steps in the midsection. Instead, such golf shafts may have a constant taper rate through the midsection from the butt portion to the tip portion. Such golf shafts may be referred to as stepless golf shafts. To buyers, stepless steel golf shafts may be considered a more premium shaft than stepped steel golf shaft.

SUMMARY

In a feature, a stepless golf shaft includes: a butt portion having: a proximal end configured to be attached to a golf grip; and a distal end; a tip portion having: a distal end configured to be attached to a golf club head; and a proximal end; and a midsection connecting the proximal end of the tip portion with the distal end of the butt portion, the midsection including: a first portion having a first outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a first taper rate and not having any step changes in the first outer diameter; and a second portion having a second outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a second taper rate and not having any step changes in the second outer diameter, where the second taper rate is different than the first taper rate.

In further features, a point where the midsection changes from the first taper rate to the second taper rate is half way between the distal end of the butt portion and the proximal end of the tip portion.

In further features, a point where the midsection changes from the first taper rate to the second taper rate is closer to the butt portion than to the tip portion.

In further features, a point where the midsection changes from the first taper rate to the second taper rate is closer to the tip portion than to the butt portion.

In further features, the first taper rate is greater than the second taper rate.

In further features, the first taper rate is less than the second taper rate.

In further features, the midsection further includes a third portion having a third outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a third taper rate and not having any step changes in the third outer diameter.

In further features, the third taper rate is different than the second taper rate.

In further features, the third taper rate is different than the first taper rate and the second taper rate.

In further features, lengths of the first, second, and third portions are equal.

In further features, a first length of a first one of the first, second, and third portions is one of greater than and less than a second length of a second one of the first, second, and third portions.

In further features, the midsection further includes a fourth portion having a fourth outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a fourth taper rate and not having any step changes in the third outer diameter.

In further features, a first length of a first one of the first, second, third, and fourth portions is one of greater than and less than a second length of a second one of the first, second, third, and fourth portions.

In further features, an outer diameter of the tip portion is tapered.

In further features, the first and second portions are frustoconical.

In further features, an outer diameter of the butt portion is not tapered.

In further features, an outer diameter of the tip portion is not tapered.

In further features, a first thickness of walls of the butt portion is less than a second thickness of the tip portion.

In further features, a thickness of walls of the first portion increases in the direction of the proximal end of the tip portion.

In further features, a thickness of walls of the second portion increases in the direction of the proximal end of the tip portion.

Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of an example stepless golf shaft having a midsection with one taper rate;

FIG. 2 is a perspective view of an example stepless golf shaft having a midsection with two different taper rates;

FIG. 3 is a perspective view of an example stepless golf shaft having a midsection with two different taper rates;

FIG. 4 is a perspective view of an example stepless golf shaft having a midsection with two different taper rates;

FIG. 5 is a perspective view of an example stepless golf shaft having a midsection with two different taper rates;

FIG. 6 is a perspective view of an example stepless golf shaft having a midsection with two different taper rates and a tapered tip portion;

FIG. 7 is a perspective view of an example stepless golf shaft having a midsection with three taper rates;

FIG. 8 includes a perspective view of an example stepless golf shaft having a midsection with four taper rates and an example graph of wall thickness; and

FIG. 9 is an example illustration of a method of manufacturing a taper in an outer portion of a stepless golf shaft.

In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

A stepless golf shaft can include a midsection with a constant taper rate. Adding more taper rates may increase manufacturing cost as manufacturing time and complexity may increase, and additional tooling (e.g., dies) may be required, etc.

The present application involves a stepless golf shaft having a midsection including two or more sections with two or more taper rates, respectively. By using multiple taper rate tools (e.g., dies), a golf shaft can be made that includes multiple taper rates within the midsection (or transitional section). By using multiple taper rates in the transitional section, more design freedom is provided, and different ball flight and performance characteristics can be achieved, such as launch angle, spin rate, etc. Changes in taper rates from one taper rate to another can occur anywhere in the transitional section of the golf shaft.

FIG. 1 is a perspective view of an example stepless (e.g., steel) golf shaft having a midsection with only one constant taper rate. As stated above, the midsection may also be referred to as a transitional section or transitional portion.

FIG. 2 is a perspective view of an example stepless (e.g., steel) steel golf shaft having a midsection with two taper rates. The stepless golf shaft is generally cylindrical. Generally cylindrical may mean including one or more cylindrical portions and multiple (two or more) frustoconical portions. The frustoconical portions have different outer taper rates and correspond to tapered portions of the stepless golf shaft.

As shown, the stepless golf shaft includes a butt portion 204 and a tip portion 208. The stepless golf shaft may be formed from a hollow cylindrical tube and machined into a final form discussed below, such as via multiple dies.

An outer diameter of the butt portion 204 is greater than an outer diameter of the tip portion 208. A thickness of walls of the tip portion 208 may be greater than a thickness of walls of the butt portion 204. This may be attributable to the reducing of the diameter of the hollow cylindrical tube at the tip portion 208.

The butt portion 204 may be cylindrical (not tapered/frustoconical), and the tip portion 208 may be cylindrical (not tapered/frustoconical). In various implementations, one or both of the butt portion 204 and the tip portion 208 may be tapered (frustoconical).

A golf club head can be attached (e.g., adhered) to the distal end of the tip portion 208. A golf grip can be attached (e.g., adhered) to the proximal end of the butt portion 204.

A midsection 212 is disposed between the distal end of the butt portion 204 and the proximal end of the tip portion 208. Distal and proximal as used herein may be used with respect to where a golf grip would be attached. The midsection 212 may also be referred to as a transition portion. The midsection 212 begins a first predetermined non-zero distance (e.g., at least 3 inches) away from the distal end of the butt portion 204 and ends a second predetermined distance (e.g., at least 3 inches) away from the proximal end of the tip portion 208.

An outer diameter of the midsection 212 decreases from the distal end of the butt portion 204 to the proximal end of the tip portion 208. The midsection 212 includes two or more different taper rates. In other words, the midsection 212 includes two or more different rates of linear decrease of outer diameter.

In the example of FIG. 2 , a first portion 216 of the midsection 212 has a first taper rate, and a second portion 220 of the midsection 212 has a second taper rate that is different than the first taper rate. The first and second rates are non-zero such that the first and second portions 216 and 220 are frustoconical and non-cylindrical.

In the example of FIG. 2 , the first taper rate is shown as being greater than the second taper rate. The present application, however, is also applicable to the first taper rate being less than the second taper rate. FIG. 3 includes an example perspective view of the first taper rate being less than the second taper rate.

Referring back to FIG. 2 , a location along the midsection 212 where the taper rate changes may be referred to as a change point (labeled change in FIG. 2 ). As shown in FIG. 2 , the midsection 212 includes one change point in the example of the midsection 212 having two different taper rates. The change point can be in the middle of the length of the midsection 212 (measured axially) as shown in FIG. 2 . In this example, the length of the first portion 216 is the same as the length of the second portion 220.

Alternatively, the change point can be closer to the distal end of the butt portion 204 or closer to the proximal end of the tip portion 208. FIG. 4 includes an example illustration of the change point being closer to the butt portion 204. FIG. 5 includes an example perspective view of the change point being closer to the tip portion 208. Different change points may provide different performance characteristics.

As stated above, the tip portion 208 may also be tapered. FIG. 6 includes a perspective view of an example implementation of the tip portion 208 also being tapered such that its outer diameter decreases from the proximal end of the tip portion 208 to the distal end of the tip portion 208. The taper rate of the tip portion 208 may be different than the taper rates of the first and second portions 216 and 220, different than one of the taper rates of one of the first and second portions 216 and 220, or the same as one of the taper rates of one of the first and second portions 216 and 220.

In various implementations, the midsection 212 may include two or more change points. FIG. 7 is a perspective view of an example stepless golf shaft including two change points. In this example, the midsection 212 includes a first portion 704 that has a first taper rate, a second portion 708 that has a second taper rate, and a third portion 712 that has a third taper rate. The first, second, and third taper rates are non-zero such that the first, second, and third portions 704, 708, and 712 are frustoconical and non-cylindrical. The first taper rate is different than the second taper rate, and the second taper rate is different than the third taper rate. The tip portion 208 may be tapered or non-tapered. The change points may be such that the first, second, and third portions 704, 708, and 712 have equal lengths. Alternatively, one or two of the first, second, and third portions 704, 708, and 712 may be longer than or shorter than one or more others of the first, second, and third portions 704, 708, and 712.

While the example of one and two change points are provided, the present application is also applicable to three or more change points. FIG. 8 is a perspective view of an example stepless golf shaft including three change points. In this example, the midsection 212 includes a first portion 804 that has a first taper rate, a second portion 808 that has a second taper rate, a third portion 812 that has a third taper rate, and a fourth portion 816 that has a fourth taper rate. The first, second, third, and fourth rates are non-zero such that the first, second, third, and fourth portions 804, 808, 812, and 816 are frustoconical and non-cylindrical.

The first taper rate is different than the second taper rate, the second taper rate is different than the third taper rate, and the third taper rate is different than the fourth taper rate. The tip portion 208 may be tapered (frustoconical) or non-tapered (cylindrical). The change points may be such that the first, second, third, and fourth portions 804, 808, 812, and 816 have equal lengths. Alternatively, one or more of the first, second, third, and fourth portions 804, 808, 812, and 816 may be longer than or shorter than other ones of the first, second, third, and fourth portions 804, 808, 812, and 816.

Stepless, as used herein, may refer to a gradual (e.g., approximately linear) decrease in outer diameter. This is different than a step change in outer diameter, such as a change in outer diameter that is greater than a predetermined amount. The stepless golf shaft may not include any step changes in outer diameter where a change in outer diameter is greater than the predetermined amount.

Stepless golf shafts may be manufactured, for example, using one or more rotating dies having respective taper rates. A golf shaft may be fed (axially) into the rotating die, and the rotating die may stamp the outer portion of the golf shaft radially inward to taper the outer portion of the golf shaft. The rotating die may include two or more different sets of tapered portions as to form the two or more tapered portions of the shaft. This manufacturing method is different than the manufacturing method used to create stepped golf shafts, where cylindrical dies may be used to create step decreases in the outer diameter of a golf shaft.

Because the golf shaft may begin as a cylindrical tube, thickness of a wall of the golf shaft may increase as outer diameter decreases and vice versa. For example, in the example of FIG. 8 , the butt portion 204 may have a first thickness. The first portion 804 may increase in thickness moving toward the tip portion 208. The second portion 808 may increase in thickness moving toward the tip portion 208. The third portion 812 may increase in thickness moving toward the tip portion 208. The fourth portion 816 may increase in thickness moving toward the tip portion 208. The tip portion 208 may have a second thickness that is greater than the first thickness of the butt portion 204. FIG. 8 also includes a graph of example wall thickness along the length of the stepless golf shaft.

FIG. 9 is an example illustration of a method of forming a taper (tapered portion) in an outer portion of a stepless steel golf shaft. As discussed above, a stepless steel golf shaft may be formed originally from a hollow cylindrical steel tube 904 of a predetermined length and having a uniform wall thickness. A mandrel 908 may be inserted into the interior of tube 904 and hold the tube 904 stationary during shaping of the tube to form a stepless golf shaft.

The mandrel 908 and the tube 904 are linearly (axially) inserted into a die 912. For example, the mandrel 908 and the tube 904 may be actuated incrementally into the die 912 by a predetermined axial distance per increment. The die 912 may include two half-circle portions having interior portions 916 tapered as to form a taper rate on the tube 904. While the example of two half-circle portions is provided, the present application is also applicable to other die configurations, such as four quarter-circle portions, etc.

The die 912 may be rotated as illustrated by arrow 920 and opened and closed as illustrated by arrows 924 as the tube 904 is fed into the die 912. The interior portions 916 of the die 912 contacting the exterior of the tube 904 taper the outer portion of the tube 904 that contacts the die 912. An example tapered portion 928 formed from the die 912 is shown on the right in FIG. 9 . Tapering the outer portion increases outer wall thickness.

Different dies with different interior portions tapered differently are used to create different taper rates, such as in the midsection, the tip portion, the butt portion, and the tapered portions above of a stepless golf shaft.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.” 

What is claimed is:
 1. A stepless golf shaft, comprising: a butt portion having: a proximal end configured to be attached to a golf grip; and a distal end; a tip portion having: a distal end configured to be attached to a golf club head; and a proximal end; and a midsection connecting the proximal end of the tip portion with the distal end of the butt portion, the midsection including: a first portion having a first outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a first taper rate and not having any step changes in the first outer diameter; and a second portion having a second outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a second taper rate and not having any step changes in the second outer diameter, wherein the second taper rate is different than the first taper rate.
 2. The stepless golf shaft of claim 1 wherein a point where the midsection changes from the first taper rate to the second taper rate is half way between the distal end of the butt portion and the proximal end of the tip portion.
 3. The stepless golf shaft of claim 1 wherein a point where the midsection changes from the first taper rate to the second taper rate is closer to the butt portion than to the tip portion.
 4. The stepless golf shaft of claim 1 wherein a point where the midsection changes from the first taper rate to the second taper rate is closer to the tip portion than to the butt portion.
 5. The stepless golf shaft of claim 1 wherein the first taper rate is greater than the second taper rate.
 6. The stepless golf shaft of claim 1 wherein the first taper rate is less than the second taper rate.
 7. The stepless golf shaft of claim 1 wherein the midsection further includes a third portion having a third outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a third taper rate and not having any step changes in the third outer diameter.
 8. The stepless golf shaft of claim 7 wherein the third taper rate is different than the second taper rate.
 9. The stepless golf shaft of claim 7 wherein the third taper rate is different than the first taper rate and the second taper rate.
 10. The stepless golf shaft of claim 7 wherein lengths of the first, second, and third portions are equal.
 11. The stepless golf shaft of claim 7 wherein a first length of a first one of the first, second, and third portions is one of greater than and less than a second length of a second one of the first, second, and third portions.
 12. The stepless golf shaft of claim 7 wherein the midsection further includes a fourth portion having a fourth outer diameter that gradually decreases in the direction of the proximal end of the tip portion at a fourth taper rate and not having any step changes in the third outer diameter.
 13. The stepless golf shaft of claim 12 wherein a first length of a first one of the first, second, third, and fourth portions is one of greater than and less than a second length of a second one of the first, second, third, and fourth portions.
 14. The stepless golf shaft of claim 1 wherein an outer diameter of the tip portion is tapered.
 15. The stepless golf shaft of claim 1 wherein the first and second portions are frustoconical.
 16. The stepless golf shaft of claim 1 wherein an outer diameter of the butt portion is not tapered.
 17. The stepless golf shaft of claim 1 wherein an outer diameter of the tip portion is not tapered.
 18. The stepless golf shaft of claim 1 wherein a first thickness of walls of the butt portion is less than a second thickness of the tip portion.
 19. The stepless golf shaft of claim 1 wherein a thickness of walls of the first portion increases in the direction of the proximal end of the tip portion.
 20. The stepless golf shaft of claim 1 wherein a thickness of walls of the second portion increases in the direction of the proximal end of the tip portion. 